2015 is going to be remembered in the history of space missions as the year of two first encounters. One, in July, when New Horizons will finally reach Pluto and make one of the flybys more awaited in the exploration of our Solar System. The other, maybe less glamourous but by no means less important, will happen months before that, when NASA’s spacecraft Dawn will reach Ceres, the largest body in the asteroid belt.
The Dawn mission, which belongs to the NASA’s Discovery Program, is remarkable under many aspects. First of all, Dawn targets a specific area, that extensive region between Mars and Jupiter that goes under the name of asteroid belt, focusing on the study of its two largest celestial bodies, Vesta and Ceres. The objective is to find out more about the early history of the Solar System by exploring two protoplanets that have evolved in different ways, with the first looking similar to inner planets like Mars, and the second with the characteristics of Saturn’s icy moon. As NASA explains in detail on the mission’s official webpage, this is not just a voyage in space, but also in time.
“Ceres is going to be a really cool-looking object when we get there. Because Ceres contains a lot of water ice near its surface, periodic defrosting may have relaxed the planetoid’s features, erasing its older craters. Maybe we’re going to have a Salvador Dali planet, where everything’s kind of melted.” (Mark Sykes, CEO of the Planetary Science Institute and Dawn mission scientist)
Another important novelty of Dawn regards its propulsion. Differently from the majority of rockets, whose engines are powered by chemical reactions, Dawn uses Ion engines, and therefore, electric fields. The main difference between the two is that chemical reaction engines are powerful but not very efficient energy-wise; on the contrary, spacecrafts like Dawn can travel for years, and cover huge distances, before running out of fuel.
“Now, finally, we have a spacecraft on the verge of unveiling this mysterious, alien world. Soon it will reveal myriad secrets Ceres has held since the dawn of the solar system.” (Marc Rayman, Dawn’s mission director)
Dawn visited Vesta from 2011 to 2013, having a few surprises. Ceres looks seemingly intriguing. It is thought to have a liquid ocean under its surface, for example, and this could hint at some forms of life. Water vapour has been recently detected. Moreover, scheduled for a close encounter in March 2015, the spacecraft has already glimpsed some odd stuff on the protoplanet’s surface. On Jan. 13 Dawn shot a photo with a mysterious white spot clearly visible, leaving the world puzzled. But Ceres promises to have in store even more.